EE228a - Fall 2001 Communication Networks

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EE228a - Fall 2001 Communication Networks

• Prof. Jean Walrand
• Department of EECS
• University of California
• Berkeley

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Course Objectives Contents

• Explain Internet and related networks
• Models and Evaluation
• Technology
• Links ADSL, Cable Modem, Optical
• LANs Ethernet
• Routers, Switches
• Protocols
• Routing, Transport, Applications

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Organization

• One lecture every week W 230 430
• Grading Quizzes 30, 2 Midterms 30, Project
  Report 20, Project Presentation 20
• Instructor
• Prof. Jean Walrand OH M 1100 1200
• Web site See Prof. Walrands home page

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Contents

• 8/29 How Internet Works
• 9/05 Ethernet, ATM, ADSL, Cable Modems
• 9/12 Models, Analysis, Simulation
• 9/19 Routing OSPF, BGP, Ad Hoc,
• 9/26 Transmission Control
• 10/03 Switching Midterm 1
• 10/10 Optical Networks
• 10/17 Wireless Networks
• 10/24 Networks and Services Management Midterm
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• 10/31 TM, NP, SAN, etc.
• 11/07,11/14, 11/28 Student Presentations

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Introduction

• Web
• Voice over IP

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Web

• Example
• Locating Resource DNS
• Connection
• End-to-end
• Packets
• Bits
• Points to remember

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Web Example

• Click -gt get page
• page from localor remote computer
• linkhttp//cnn.comspecifies - protocol
  (http) - location (cnn.com)

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Web Example

• Click -gt get page
• page from localor remote computer
• linkhttp//cnn.comspecifies - protocol
  (http) - location (cnn.com)

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Web Example

• Click -gt get page
• page from localor remote computer
• linkhttp//cnn.comspecifies - protocol
  (http) - location (cnn.com)

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Web Locating Resource

• cnn.com is the name of a computer (and,
  implicitly, of a file in that computer)
• To find the address, the application uses a
  hierarchical directory service called theDomain
  Name System

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Web Connection

• The protocol (http) sets up a connection between
  the host and cnn.com to transfer the page
• The connection transfers the page as a byte
  stream, without errors pacing error control

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Web End-to-end

• The byte stream flows from end to end across many
  links and switches routing ( addressing)
• That stream is regulated and controlled by both
  ends retransmission of erroneous or missing
  bytes pacing

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Web Packets

• The network transports bytes grouped into packets
• The packets are self-contained and routers
  handle them one by one
• The end hosts worry about errors and
  pacingDestination sends ACKsSource checks
  losses

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Web Bits

• Equipment in each node sends the packets as a
  string of bits
• That equipment is not aware of the meaning of the
  bits

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Web Points to remember

• Separation of tasks
• send bits on a link transmitter/receiver clock,
  modulation,
• send packet on each hop framing, error
  detection,
• send packet end to end addressing, routing
• pace transmissions detect congestion
• retransmit erroneous or missing packets acks,
  timeout
• find destination address from name DNS
• Scalability
• routers dont know about connections
• names and addresses are hierarchical

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Voice Over IP VoIP

• General Operations

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VoIP General Operations

• Gateways must reproduce the signaling and voice
• Signaling dialed digits, dial tone, ringing
• Voice Packetize and absorb delay jitter
• Note Routing problem